Sound deadening or absorbing wallboard



Oct. 4, 1960 2. E. M. NUORIVAARA 2,954,338

SOUND DEADENING OR ABSORBING WALL-BOARD Filed May 8, 1956 United StatesPatentO "ice SOUND DEADENING R ABSORBING WALLBOARD Zachris Enzio MikaelNuorivaara, Overboelare-Grammont, Belgium, assignor to SvenskaTandsticks Aktiebolaget, Jonkoping, Sweden, a Swedish joint-stockcompany Filed May 8, 1956, Ser. No. 583,420

Claims priority, application Sweden May 18, 1955 1 Claim. (Cl. 181-33)The invention relates to a sound-reflection counteracting board. Moreparticularly, the invention relates to a board for lining ceilings andwalls in rooms in order to improve the acoustic conditions by thespecial structure of the board.

For facing walls and ceilings different kinds of wallboard are used,which may be either hard or more or less porous. The hard wallboardusually has a thickness of about 6 mm. and it is ordinarily made withoutany special covering layer. It is usual, however, to paint the board,especially as it does not absorb the paint. This board has a hardsurface and reflects sound to a high degree. The more porous wallboardusually has a thickness of 6-13 mm. These boards need a surface layer,but as they absorb paint too much they are usually faced with paper andsometimes also painted. Without any surface layer these boards have acertain capacity of absorbing sound, but by applying the more densepaper the sound insulation is reduced, and particularly in large roomsthe acoustics deteriorate and the sound reflection causes a disturbingeffect.

A principal object of the present invention is to provide a board of thecharacter stated, which considerably reduces the echo effect bysplitting the sound waves in different directions.

An additional object of the invention is to provide a board, whichreduces the reflected waves by increasing the absorption surface.

Another object of the invention is to provide a sound deadening board,which is simple in its construction and inexpensive in its manufacture.

A further object of the invention is to provide a sound deadening board,which maintains its form in spite of impressions therein.

A still further object of the invention is to provide a cheap sounddeadening board, which has an ornamented surface.

With these and other objects in view, as will appear hereinafter, myinvention consists in certain steps of the manufacture and arrangementsof the porous board as will appear from the following description, claimand the accompanying drawing, in which Figure 1 is a plan view of a partof a sound absorbing board according to one embodiment of the invention,and

Figure 2 is a section along the line IIII in Figure 1 on an enlargedscale.

In the drawing, 1 indicates a fibre board or wallboard, 2 is a coveringlayer glued to the board, 3 a series of parallel ridges and 4 a seriesof other parallel ridges perpendicularly thereto so that pyramidalrecesses are formed between the ridges.

Experiments have shown that the covering of the board in connection withthe pressing operation in a wallboard press involves severaldifficulties, and the board is therefore made in the ordinary way andsubjected in dry condition to the steps according to the invention.

Patented Oct. 4, 1960 The covering layer of lining may consist of sheetsof any suitable material, such as fabric, plastic, metal foils, but itis preferred to use a porous paper which in the manufacture is weaklyglued and therefore, in contact with the glue, can be stretchedsufficiently without bursting when thedepressions are formed.

Before the paper is placed on the board a glue layer is applied eitherto the board or to the paper, whereafter the paper is rolled onto theboard and the depressions are made. As the porous board is rathereleastic, the depressions would be partly levelled out, if they are notimmediately made stiff and permanent in some way. For this reason athermosetting resin of any known and suitable kind is used, which can behardened or cured by heat and the press member for making the depressionis heated so that the glue is hardened during the pressing operation andstiffens the walls of the depressions.

This operation may be performed in a press similar to an ordinarywallboard press but with only the one press plate heated and providedwith an uneven surface corresponding to the desired pattern in theboard. The same operation, however, may be carried out by feeding theboard between two press rollers, one of which being heated electricallyor by steam and having its surface patterned. In order to obtain thepattern shown in the drawing the one press roller may be provided on itssurface with two series of grooves, one series perpendicular to theother, so that the surface is covered by adjacent, upstanding pyramids.The depressions in the board will thereby be pyramidal, but it isobvious that the board may also be provided with depressions of aconical or other suitable form.

When the sound waves reach a wall or a ceiling having a surface of suchdepressions, the waves are collected towards the bottom of thefunnel-shaped depressions, and for absorbing the waves, holes 5extending from the bottom and partly or entirely through the board arebored or punched so that the waves enter the holes and pass through theside walls thereof into the porous board. Another part of the waves arereflected and split up in several directions, and these feeble soundwaves are only of an inconsiderable inconvenience. When they reach thenext wall they are rapidly and efiiciently deadened.

The boards may be prepared in the following way. After the boardsobtained from the wallboard press are cooled sufficiently to prevent toorapid setting of the glue a board is introduced between two feed rollersand forwarded on a table, on which the fore end first passes a gluestation, where the glue is applied either by spraying or by a brush orroller. In the next station the web is supplied and pressed by a freelyrotating roller against the glue layer so as to be at least partlyimpregnated with glue and capable of being somewhat stretched. In thethird station the board thus coated is introduced between the patternroller and a counterroller, of which the former is heated to such a hightemperature, such as to 200 C., and rotates with such a low speed thatthe binding agent is cured between the rollers sufficiently to stiffenthe walls of the depressions and prevent the compressed material fromexpanding.

What I claim is:

A sound-reflection counteracting wallboard, comprising essentially astiff porous fibre board formed with shallow depressions coveringsubstantially the entire surface of one side of the board and narrowingcontinuously from all sides to a point in the center of the depression,a layer of a cured thermo-setting binding agent covering the surface ofthe board provided with the depressions for reinforcing the surfaces ofthe de- J; pressions and maintaining their form, and a thin coveringlayer glued to the entire surface provided with the depressions and of asuflicient ductility to be depressed Without breaking, said board beingprovided with holes extending from the lowest portion of saiddepressions at 5 least partly through the board.

References Cited in the file of this patent UNITED STATES PATENTS1,781,797 Williams Nov. 18, 1930 10 Cunnington Apr. 5, 1938 Wagner Jan.16, 1940 Davies Apr. 24, 1951 Gerard Sept. 22, 1953 FOREIGN PATENTSGreat Britain Sept. 13, 1950 Germany Oct. 11, 1951

